The use of shellac in water-based flexographic inks is well known. However, such inks have several disadvantages, notably marginally acceptable bond strength and undesirably high viscosities. Moreover, as inks are used, there is a buildup of ink on the press cylinders and shellac-based inks are difficult to remove from the cylinders, even with alkaline cleaning solutions.
Acrylic resins on the other hand can be made water-dispersible, but are generally incompatible with shellac and do not offer the advantages of shellac such as adhesion, gloss and printability.
Ideally, a copolymer of these two incompatible polymers would be very useful for preparing water-based inks, but such copolymers have not been produced to date.